Problem with admin-ajax returning (white) spaces

Hi,

I created a plugin which was working fine when suddenly my admin-ajax is not returning the ajax callback function properly anymore. My wp on the server is still working properly, but the one i have in my computer doesnt. i transferred my files from server to local but the problem still exist. My admin-ajax is still retruning white spaces. for example

function test() {
echo ‘ok’;
die();
}

when i alert this with javascript it alerts something like “(space)o(space)k” which make my plugin really useless. any ideas how i can fix this?